Influence of fat level and type of carbohydrate on the capacity of pectin in lowering serum and liver lipids of young rats

Abstract

The effect of pectin on lowering cholesterol and fat concentration in tissues of the rat was investigated in relation to the level of fat and the type of carbohydrate. Groups of rats were fed nutritionally complete diets containing equal protein: energy, varied with 5% (low-fat, 2% corn oil plus 3% beff tallow) or 20% (high-fat, 2% corn oil plus 18% beef tallow) fat and cornstarch or sucrose as carbohydrate for 2 weeks. Although there were no interactions, the feeding of pectin reduced the cholesterol level in liver and serum from dietary cholesterol to a greater degree in rats fed the low-fat than in those fed the high-fat diet. This effectiveness also varied with type of carbohydrate. In the low-fat diet, this effectiveness was higher with sucrose than with cornstarch, but in the high-fat diet, it was reversed. The size of perirenal fat pads and the concentrations of total liver lipid and cholesterol were less in rats fed the high-fat pectin diet than in those fed the high-fat diet without pectin, indicating that pectin also had an ability to lower fat absorption. When the level of serum alkaline phosphatase was lowered, pectin was more effective in lowering cholesterol level. This phenomenon, however, seemed due to the type of carbohydrate and fat rather than the cholesterol in the diet. Dietary cholesterol had no effect on the size of perirenal fat pads, but increased liver lipid content greatly in rats fed the high-fat diet. Dietary pectin increased the rate of removal of serum cholesterol, and a similar trend was shown in liver cholesterol which had accumulated from the pre-fed hyper-cholesterol diet.